Interpretive Summary: Cotton producers receive the majority of their income by selling the lint from their cotton crop. The cottonseed is increasingly an important additional source of income for cotton producers due to the growing demand by the dairy and restaurant industries for whole cottonseed and cottonseed products. Previous research has demonstrated the benefits that early planting, different varieties and irrigation have upon increasing lint production. Scientists at USDA, ARS, Crop Production Research Unit, Stoneville, MS and Commodity Utilization Research Unit, New Orleans, LA have conducted study to determine how varying irrigation regimes interacted with different cotton varieties to affect the composition of the cottonseed produced. Although irrigation, in and of itself, affected many of the seed composition traits, the effect that irrigation had on seed composition varied depending upon the cotton variety being grown. Most of the six varieties tested responded in a similar fashion to irrigation for the various seed composition traits. However, the variety ST 5599BR often exhibited a different irrigation response than the other varieties, particularly for the different fatty acid components. Given the proper economic incentives, producers could potentially pair a particular variety with appropriate production strategies to produce seed with desired composition traits. The results from this research can be used by cotton researchers, breeders, extension specialists, consultants, and producers as an unbiased source of information to aid in making cotton production decisions.

Technical Abstract:
The value of whole cottonseed and cottonseed products has increased as demand has grown from the dairy and food related industries. Although cottonseed composition has previously been documented to be affected by variety, planting date, and irrigation, interactions between varieties and irrigation regimes hasn’t been adequately described. Six different varieties were planted on two planting dates and grown under irrigated or dryland conditions to document how varieties interacted with irrigation regimes to impact various seed composition traits. Variety was a major source of variation for all the seed composition traits quantified. Individual seed mass variation among the varieties could explain some of the seed composition variation observed, particularly for protein. For many of these seed composition traits, variety also statistically interacted with irrigation regimes to impact trait expression. Most seed composition traits of the varieties generally responded in the same direction to irrigation, but there was sufficient variety variation in the degree of that response that significant interactions were produced. ST 5599BR often exhibited a different degree of the irrigation response than the other varieties, particularly for the different fatty acid fractions. These results indicate that a proper pairing of varieties and management practices could be utilized to help achieve desired seed composition traits. Although lint production is the primary economic incentive for cotton producers, improved cotton seed composition would offer a consistent and reliable secondary revenue stream for producers.